Kriesi changed the behaviour for mobile devices a bit (you need to update Flashlight to 1.4 first). The changelog says:

js/avia_fullscreen_slider.js - modified the handling of sidebar and mini content boxes on mobile devices. since most mobile devices made problems using the CSS "fixed" layout those elements are now positioned "absolute" instead. looks a little less sophisticated on moble devices but the usability gain is huge

I really doubt that Flashlight will turn responsive in the future though…